"I've stuck my neck out here and I don't intend to make public information I've given to the police," Mr Blewitt said.

Mr Blewitt says Mr Wilson should back up his claim about Ms Gillard's innocence by waiving legal privilege.

"If you are so certain, Mr Wilson, that she has nothing to answer then you should immediately release Nick Styant-Browne, Slater & Gordon and another law firm Maurice Blackburn of client privilege confidentiality," he said.

"Notify them that you wish to allow them to release any documents or files that they have."

Mr Blewitt denied any personal vendetta against Ms Gillard.

He said he had requested immunity from prosecution before agreeing to hand over information because he was a party to fraud although he did not financially gain from it.

Former industrial lawyer Harry Nowicki, who is writing a book about the union's history, paid Mr Blewitt's expenses so he could return to Australia.

"All it is for me is an air fare and a few nights' accommodation. That's not serious money," Mr Blewitt said.